Semicontinuous dry-rendering and meal-manufacturing process



Fb. 3, 1931. W B ALLBR|GHT 1,791,439

SEMICONTINUOUS DRY RENDERING AND MEAL MANUFACTURING PROCESS Filed March 30, i925 maw @www www im relatively small particles.

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Winnen s. enrasnrerrnor cnrceeo, immers SEIVIICONTINUOUS DRY-RENDERING AND MEAL-MANUFACTURING PROCESS Application filed March V30, 1925. Serial No. 19,378.

rIhe'present invention relates to semi-continuous processes of dry rendering, and manufacturing meal.

More particularly the invention relates to emi-continuous processes for dry rendering and oil containing solids, such as animal parts, packing house effal and the like by utilizing batch cookers or driers, expressing the hea'A l solids in hydraulic curb or continuous hi n pressure presses, and reducing` the solids from the press to a meal.

in the production of kettle rendered lard it has for many years been the practice tok hash or cut the fat con ning materials into The cut material then heated to melt the fats and to remove l the me' re by the application of ect heat, usually in steam jacketed cooliliettles, while the evolved gases and vapors permitted to escape, and the material is agitated rotating stirrers. The heating and stirring is carried on until the craclings are browned or slightly crisped, and the material is then discharged into a percolator er strainer .where the free hot fats and oils are drained off. rthe cracklings are then pressed in suitable .hydraulic or high pressure screw presses to remove the remaining fats. Lards and fats produced in this well known manner are usually not white in color.

in my United States patent numbered l, 3 7.675, issued ctober i', 1919, I have disclosed an improved semi-continuous process for making high grade edible fats of pure white color without the `use of bleaching agents. In handling fats, when the materials are heated materially above 220 to 240 degrees Fahrenheit after the moisture content of the cracklings is reduced below the range of l5 to 20 percent, the rendered products are discolored and injured in quality by absorption of glues. The moisture content in the solids also bears a close relation to the quantity of fat-s which may be expressed from the cracklings. lf the moisture content is too high, when the materials are expressed in continuous high pressure screw presses,

^' mucilaginous and glue-like substances are expressed with the fats, and a poorly pressed residue containing too much fat is'obtained. if on the other hand, the cooking or drying is continued in the usual melter or dryer until the clear fats Without glues may be eX- pressed satisfactorily in a continuous screw press or hydraulic press, the temperatures rise as the moisture content of the material is reduced to the proper stage for expressing, and discoloration of the fats or lard occurs. '60 lVhen handling mixture of materials which should'produce high grade fats, such as tongue trimmings, fat from middle beef guts, beef cooler trimmings, lungs, rennets, round ann middle guts, bung guts, and dirty oleo fats, at temperatures of 260 degrees Fahrenheit with a relatively low moisture content, a distinct discoloration occurs. Accordingly, in the improved process set forth in my patent, the cracklings are discharged from the cooker or heating unit while Ythe moisture content is still too high for satisfactory eX- pressing in a high pressure screw press, and before seriously discoloring temperatures are acquired. The free hot fats are then drained from vthe cracklings in a percolator, and the cracklings are dried and tou'ghened to the proper point by spreading them out in contact with the air. As soon as the cracklings are properly dried and toughened, they are passed continuously through a heating unit into any Well known high pressure screw press commonly used for this purpose. A very satisfactory pressed crackling and a high grade of edible fat is produced in this manner.

It has long been well known that fresh animal parts of all kinds, when dry rendered, give oil' vapors which are not offensive. ln many slaughtering houses these vapors are 9G permitted to escape directly to the air, and the rendering of fresh parts may even b-e carried out in open kettles without generation of obnoxious odors. ln the production of lower grade tallow, however, especially in a5 smaller establishments, the materials to be rendered are frequent-ly in more or less decomposed state when put into the dry rendering cookers or melters. For this reason it has eeen long the practice to use enclosed 109 steam jacketed melters in which the gases have been withdrawn as evolved and condensed or otherwise treated to effect deodorization. It is also the practice to conline vapors in closed cookers in large slaughtering houses so that the steam and generated vapors may be conducted out of the buildings.

The solid residue from the prior dry rendering processes is of much higher than the residue from the well known wet rendering processes. lVhen suitable materials are rendered as set forth in my above mentioned patent, the cracklings may be made into food fit for human beings. For lower grade products, the residue is made into stock food, and fertilizers, and it has been for many years well known that the meals produced in the dry rendering processes are superior in quality to the meals from the tankage of wet rendered products. This is dueto the fact that the addition of water in digesting in the well known wet rendering methods causes recomposition of the material, dissolves the water soluble contents, and leaves a more or less decomposed residue for the manufacture of meal which is of low grade.

To utilize these well known advantages of dry rendering, in the production of higher grade meals than are obtainable by wet rendering methods, and where the quality of fats may be sacrificed, particularly in the handling of inedible animal parts, such as the entrails, lungs, livers, offal, shop scraps, condemned carcasses, condemned viscera, tripe and guts hashed, rennets, bruised fat, stomachs, bladders, slunks, tripe trimmings, pigs feet, perks hashed and washed, gullets, bung guts, cutting scrap tallow, and the like, I modify the process set forth in my patent hy'eliminating the refinements therein practiced to avoid the discoloration of the fatsl This is effected by heating the materials while confined indryers or melters until the moisture content has been lowered to the point where the fats may be effectively expressed fromthe solid residue in a continuous high pressure press. After being discharged from the dryer'- or inciter the free fats are drained away in a steam jacketed drying pan or percolator, and the solid residue is then continuously passed to a high pressure screw press or any other suitable type of press without the delay to effect further low temperature drying, set forth in my patent by spreadingthe cracklings. The fats produced in this way are discolored and of low grade.

In endeavoring to avoid the discoloration produced in the fats, I have discovered that this may be effected by a variation of my process for handling inedible er low gra-le products, which comprises separating the free hot fats from the melter or dryer before the moisture content of the crackrings or grade solids is lowered to the point where serious discoloration of fats will occur, and then continuing the heating of the residue until the moistm'e content is reduced to the required point for satisfactory expres 'nga The residue is then dropped into a draining pan and passed to a continuous press, as above set forth. The obtained in the latter stage ofthe process will be discolored, while the fats drained oli in the first stage will be high grade. The major portion of the fats will be obtjnedin the first stage, and in practice the smaller portion of the fats which will be discolored may then be m xd with the high grade fats without serious Lnfury to the grade of the mired product. In this way, the quality of the fat-s is raise d materially. In establishn'ients where largn volumes of fats are handled the discoloreii .ats may he retained separate iti-'om the hi gher grades and sold as a lower grade product.

Referring to the drawings, the gure indicates in diagram a preferred embooiment of arrangement of a1 paratus to carry out my invention.

The material to be rendered, such as entrails, lungs, condemned animal parts, oit'al, and the like, may be cut and washed thoroughly in a cutter and washer indicated at l which may he of any well known type. The cutter and washer is not essential and may be eliminated especially when treating scraps or like material containing bone. The materials are then pas 'l into hoppers an d fed into the steam jacl d melters or dryers 3 containing agitator-s 3 driven in any suitable manner to contfnuously agitato the inaterial. These driers or mrlters may be of the type disclosed in British Patents S39? of 1912 and 3662) of l9l-l, or of any other well known steam acketed typo. A jacket pref*- sure of 40 pounds per square inch gives excellent results although iis pressure may vary widely in practice. rlhe material heated and agitated in the melters in well known manner and the evolved vapors, gases and steam are withdrawn through openings al and led by pipe 5 to the or en air or a suital'ile condenser, treated to destroy any obnoxious odors, or treated in any other suitable manner.

The heating and agitation is continued until the moisture content reduced to they point where the fats maybe innnediatelv and effectively expressed from thel solid residue. in a continuous high pressure press when the quality of fats is to be disregarded. For proper expressing in high pressure rotary screw presses developing from seve: l hundred to many thousand pounds liciinch, the most satis' LJtory inoistLi-e cor .uit

is approximately from three to eight por.

cent, although this may vary widely with difierent types of presses.

Then the proper de ee of dehydration or drying has heen reached, the hotdehydrated material is discharged through discharge openings G to a steam jacketed percolator or a draining andrdrying table or tank where 'the free hot fats arev drained from the solid residue. A steam jaclreted draining table 7 is shown in the illustrative vembodiment oi' the invention. The fats may be drained from the table as in my prior patent above referred to, or in any other suitable vway. For example the fats may be drained into suitable storage vats through the drain pipe 7 As soon as the free `hot fats and oils are drained oil?, the solid residue or cracllings are'pushed into passage 8, and

pass downward to a steam jaclreted conveyor or tempering apparatus 9 such as shown in Patents :#:LlSQfl-Ql and #1,132,422 )r example, in which they are 'tui-ther heated,

i tated and iced through the conveyor by means of agitating and feeding arms 3. Frein conveyor @the hot material passes downward through l0 into a continuous ai pressure screw vpress il ogtany wellY g5 type in which the fats are expressed fr solids at pressures ranging up to several t nd pounds per'square inch or more ing a press cal-Ie containing as low sii: percent fat.

li. operation the ine-lters and deh; are fill t successively and will accord ready for discharging the material a at different times.

narg is deposited on the drai cable, th pressinay be st..

i ntinuous open tion thereof may l tain d until the last charge is expressed. villen treating materials which contain rela "t ely large pieces of hone, either betere ng or after draining and before pressing, Lt is necessary to grind the material in order to reduce the hone to a size w1 h may he handled by the press. lie hone particles, created in this manner, tend to becoine hard 1., or flint-like in character and tend to rapidly wear the press. They also are more or less indigestible and insoluble and are unsatisfactory for this reason in hoth food and fertilizer meals. Betere they can be absorbed hy the soil they must lie a sufficient tiine to decompose. Materials without the bone content, however, yreduce to high grade 'ioods and fertilizers in which all the water soleible solids ordinarily lost in wet rendering are retained.

rlhe press calre may be ground into meal in a grinder l2 to be used as stock food or fertilizer, or it may be liXivia-ted and treated to extract the glues. e: lt will be seen that semi-continuous re-;-

dering process is provided which diiiers from the process set forth in my above inentioned patent in that the quality oi' sacrificed in the present case by dry/'ing materials in the melter to a point where tl ey may be pressed from the hot solids in a screw press or hydraulic press', immediatelyv after he free hot* fats are drained away.

To raise the quality of the grease and fats obtained the operation above set forth is varied by stoppingthe agitation and `withdrawing the 'ree tats from the inciter by opening a suitably arranged drain cock in well known manner when-a substantial portionof the'iiat is released, the moisture content or" the residue Vor craclrlings is still above the point where discoloration of the tats occur. isoloration and injury toquality occurs at tie temperatures employed when the moisture percentage goes helow the range of l5 to 2O percent in thc cracklings, they critical value being apparently about 16 .per cent, while the tat temperatures exceed Q20 to 24;() decrees So lollig` the mois- O llanrenheit.` y ture content is above aoout l5 to 20 iegrees E.

no hai i doneby heating' the tats above l) d Fahrenheit.

he tree .tats are drained oil, agitaieating of the residue in the cooker,

s contiuocd Lore set forth untiltho crachtion and i llinge are reducedv to the proper moisture content for pressing, preferably in a continuous screw press. By way of a practical example of carrying out my process to procure the igher grade fats the following illustration given. Y

A standard dry cooker or melter, charged with 4200# of `Vmaterial including 400 tonouo trimmings, 500# chip Jat from mio.-

nd round beere guts, 500.11% trii..niings, ilOOr/,t lungs, 00.13. s. com.: roundv and middle guts ends, and 250.# hung gut ends, and 1250# dirty oleo fat. 'llie charge jacket steam pressure ot-iO# per squareinch for a period oi"- two hours, at theend of which time agitation was stopped, and the free fats weredrained out of the melter.' The fats discharged at a temperature of 220 degrees F ahrenheit and were high in quality. The resiof lower grade showing` a distinct discoloration. The craolrlings at this stage upon analysis showed amoisture contentot 5 percent, and were in a condition to be pressed in a screw press.

Further tests have shown that for inedible tallows, as the moisture content of cracklings approaches 16 percent, the temperature or the i'ats may range as high as 240 degrees Fahrenheit without serious injury to the inarlet value or" the tallow, while edible products d was then heated and agitated'with a should not go over 220 degrees Fahrenheit as this value of moisture is approached. In practice as the residualfmoisture percentage of a batch of usual run of inedible products, approaches sixteen percent, such for example as a charge of 4200# of materials including 500# packs, belts, rennets 3501i, 300# dirty oleo fats, 600:#- toiigue trinimin'gs, 200# lungs, 300# round and middle gut ends, 4.00# `bung gut ends, 150# cooler beef trimmings and 500# crisp fat from round and middle guts, about 80 percent of the tallows may be drawn oli as a relatively `high grade product. This condition is aproached in the usual large size fat melter of 4200 to 4500 pounds capacity after about three and one-half hours of agitation and heating of the usual charge to a temperature corresponding to approximately 40 pounds pressure in the steam jacket.

As this condition is approached the fats Will reach about 240 degrees Fahrenheit in temperature,iand when this temperature ot.' fats is reached it may be taken as a practical indication that agitation should be stopped and the `high grade inedible tallows withdrawn. After the free fats are withdrawn, agitation and heating should be resumed until the moisture content ot' the cracklings is reduced to the range for proper pressing. This finishing stage will require from l to 11/2 hours. Itwill beobvious thatthe draining of 'fats'may vbe effected at a plurality of intervalsas .the critical discoloring moisture and temperature relation is approached. For practical operation, the best results are obtained when thehigh grade fats are withdrawn from the melter with the moisture content ofthe cracklin gs ranging between 20 and 40 percent, sothat relatively unskilled laboi1 may 'bc utilized to carry out the operation without endangering the quality of fats in diterent batches bypassing the critical tenipcraturc moisturerelationship range.

Having described preferred embodiments of my invention what is desired to be secured by Letters Patent and claimed as new is:

1. The process of dry rendering fat-containing solids of animal origin which coniprises subjecting the materials to heat and `agitation While withdrawing the vapors evolved during ythe heating and agitation, continuing the application of heat and the withdrawal of vapors until the .resi lue reaches a temperature approximating but less than the temperature at which the glues and mucilaginous substances are separated from the solid residue and until the moisture content is reduced to from twenty to forty 'percent;'draining the free hot fats and oils from said residue, and then again continuing the application ot' indirect heat and the withdrawal of vapors until the moisture content of the solid residue is reduced to from three to eight percent, and then f luhjecting the residue to progressively increasing pressure to complete the separation of the fats there- `from.

2. The process of dry rendering fat-containing solids of animal origin, which consists in subjecting lthe solids to indirect heat and continuous 'agitation While simultaneously withdrawing evolved vapors until the moisture content vot' the solid residue reduced to `fromtwenty to forty percent, then draining the free fats from the solid residue,

then continuing the application of indirect heat and continuous agitation accompanied by the simultaneous further withdrawing of evolved vapors until the moisture content ci the solid residue is further reduced to troni three vto eight percent and then linaliy parating the remaining vfats troni the resi by straining and by subjecting said residue to progressively increasing pressure.

3. A semi-continuous process of dry rendering fats containing solids of animal origin, which consists in subjecting tlie'solids to indirect heat and continuous agitation while simultaneously withdrawing vapor until the moisture content of the solids contained in the material is reduced to from approximately 16 to 40' percent, then draining the free fat from the solid residue, then continuingthe application of indirect heat and continuous agitation accompanied by the simultaneous 'further withdrawing of evolved vapors until the moisture content of the solid residue is further reduced to from approximately three to fifteen percent, and then substantially imnicdiately separating the remaining fats from the residue by straining' and by subjecting said residue to progressively increasing pressure.

In testimony whereof, I atliX my signature. 

